Fully closing diaphragm



April '15, 1969 C. RODIER FULLY CLOSING DIAPHRAGM Filed Dec.

Fig .v1

////////////1 III/IA United States Patent '0 3,438,316 FULLY CLOSING DIAPHRAGM Christian Rodier, Creteil, France, assignor to Societe dOptique, Precision, Electronique et Mecanique, Paris, France, a company of France Filed Dec. 13, 1966, Ser. No. 601,458 Claims priority, application Great Britain, Dec. 29, 1965, 44,179/ 65 Int. Cl. G03b 9/06 US. Cl. 95-64 1 Claim ABSTRACT OF THE DISCLOSURE A diaphragm has three movable leaves in a cylindrical casing. Each leaf has the shape of a V and one of the two arms carries a fixed pivot on the rear surface of the leaf and the other arm has a lug on the opposite surface engaged by an operating ring in the casing. The pivot of the leaf furthest from the operating ring is mounted in the base of the casing and the pivots of the other two leaves are mounted in two plates supported in the casing between two leaves.

This invention relates to a fully closing diaphragm.

The new diaphragm allows a relatively large aperture to be fully closed with a small number of leaves, the leaf movements being controlled by a coaxial operating element providing a large angular clearance, so that a large amplitude scale is available for the aperture graduatrons.

According to the invention, the diaphragm comprises three movable leaves disposed in a cylindrical casing, the leaves all having the shape of a V, one of the two arms having a fixed pivot provided on the rear surface of the leaf while the other arm has a lug on the opposite surface for driving the leaf through an angular travel about the pivot by means of an operating ring common to the three leaves and centered in the casing, the position of the drive lug with respect to the pivot being such that the drive lug of the last leaf avoids the pivots of the other two leaves in its two end positions in which the arms of the V of each leaf are tangential to the aperture diameter or cover the centre of the diaphragm.

One specific embodiment of the diaphragm according to the invention is illustrated in the accompanying drawing and described hereinafter by way of example.

In the drawing:

FIG. 1 is a section on the line II of FIG. 2 showing the various elements in their fitting sequence and axially offset from their normal positions;

FIG. 2 is a plan view in section on the line IIII of FIG. 1 showing just one leaf;

FIG. 3 is a plan view of the diaphragm closed.

The diaphragm is mounted in a cylindrical casing 1 provided with a central aperture 1a, the operating ring 2 provided with the aperture 2a being centered in the said casing.

The diaphragm comprises three blades or leaves 3, 4 and 5, and only the central leaf 4 is shown in plan view in FIG. 2, being shown in the open position in unbroken lines.

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Each of the leaves 3, 4 and 5 has a V-profile, of which the arms 4a and 4b (FIG. 2) are substantially tangential by their inner edges to the aperture diameter when the diaphragm is open, and the outer apex of the V, e.g. 4c, is inscribed in the inside diameter of the casing 1. When the diaphragm is closed the apex formed by the inner edges of the arms of the V is in a position beyond the diaphragm center and the apex 4c is substantially tangential to the aperture diameter.

The arm 4a of the leaf 4 bears a leaf pivot 4d while the arm 4b bears a lug 4e for driving the leaf about the pivot 411. Similarly, the leaves 3 and 5 bear pivots 3d and 5d and drive lugs 3e and 52 (FIG. 1).

The pivots 3d, 4d and 5d are disposed on the rear surfaces of the leaves while the drive lugs 3e, 4e and 5e are disposed on the front surfaces.

The pivot 5d of the rear leaf 5 is directly mounted in the casing 1; the pivot 4d of the central leaf 4 is supported by a fixed plate 6 and the pivot 3d of the leaf 3 is supported by a fixed plate 7.

The two plates 6 and 7 are identical; they have three peripheral cut-outs, e.g. as denoted at reference 6a in FIG. 2. One of the cut-outs 6a of the plate 6 provides angular clearance of the drive lug 5e of the leaf 5, and two of the cut-outs of the plates 7 provide angular clearance for the drive lug 4e of leaf 4 and the drive lug 5e of leaf 5.

The plates 6 and 7 are kept stationary by means of pins 6b and 7b mounted in apertures 1b formed in the casing 1.

FIG. 2 shows that the leaf 4 has a profile 4f concentric with the pivot 4d and enabling the leaf to avoid the pivot 3d of the leaf 3; similarly, the leaf 5 avoids the pivot 4d.

The movements of the leaves 3, 4 and 5 are controlled by rotation of the operating ring 2 which has three oblong apertures 2b in which the drive lugs 32, 4e and 5e engage (FIG. 3).

The angular clearance angle A (FIG. 2) of the three leaves is limited to the possible clearance of the drive lug of one of the leaves between the pivots of the other two leaves, and this corresponds to a rotation of about 120 of the operating ring.

The small number of leaves and the considerable angular travel of the operating ring have the advantage that only a small torque is required, and this facilitates remote control of the diaphragm or its control by means of a cell.

Of course the diaphragm as described above may be modified or completed by any other suitable accessory without thereby departing from the scope of the invention.

For example, the pivots of the three leaves could be centered directly in the casing in the absence of plates to support the pivots of the first and second leaves, and

this would reduce the operating angle because at least one of the leaves themselves would avoid the pivots of the other two leaves.

Also, spacing means may be provided between the fixed plates, the casing and the operating ring to provide the required axial operating clearances.

What I claim is:

1. A fully closing diaphragm comprising three movable leaves disposed in a cylindrical casing, each of the leaves having the shape of a capital V, one of the two arms of the V having a fixed pivot provided on the rear surface of the leaf while the other arm has a lug on the opposite surface for driving the leaf through an angular travel about the pivot, an operating ring common to the three leaves driving the leaves through said lugs and mounted and centered in the casing, the drive lug of the leaf furthest from said ring being mounted in the bottom of the casing, the pivots of the other two leaves being supported respectively by two plates, each plate being mounted in the casing and between two leaves, the lug of each of the leaves being located in its two extreme positions substantially in the two radial planes passing through the center of the diaphragm and the pivots of the other two leaves.

References Cited UNITED STATES PATENTS NORTON ANSHER, Primary Examiner.

0 J. F. PETERS, IR., Assistant Examiner.

US. Cl. X.R.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.6. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,438 ,316 April 15 1969 Christian Rodier It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, line 7 "Great Britain" should read France Signed and sealed this 7th day of April 1970 (SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

